Willis will move nearly 500 employees into more than 140,000 square feet of the 110-story building. And the naming rights comes for free with the $14.50 a square foot price tag.

“Having our name associated with Chicago’s most iconic structure underscores our commitment to this great city, and recognizes Chicago’s importance as a major financial hub and international business center,” Joseph J. Plumeri, chairman and CEO of Willis Group Holdings, said in a press release. “We are delighted to be making this bold move and firmly establishing our leading presence in one of the nation’s biggest insurance markets, and it will be wonderful for all our associates to work under one roof.”